Penguins offer evidence of global warming
Sat Dec 16, 2006 10:01 AM ET



By Deborah Zabarenko, Environment Correspondent, REUTERS

MCMURDO STATION, Antarctica (Reuters) - The first Adelie penguin chicks of the
season -- black fluffballs small enough to hold in the hand -- started hatching
this month, and the simple fact that there are more of them in the south and
fewer of them further north is a sign of global warming, scientists say.

Smaller than the more majestic Emperor penguins, the Adelies have some 193
colonies that have a total population of 2.5 million breeding pairs, said
researcher David Ainley in a telephone interview from his camp at the penguin
rookery at Cape Royds in Antarctica.

"We're looking for dramatic right-hand turns (in the penguin population), which
are happening now," Ainley said. "The rate of Adelie penguin colony
disappearance is accelerating as the sea ice disappears."

As the northern sea ice vanishes and penguin populations decrease, southern
penguin colonies flourish as the sea ice loosens, making it easier for them to
dive and fish, he said.

Adelies and Emperors are the two species of penguin that live on sea ice; all
other penguins dwell in open water.

"Adelies and Emperors have the ability to cope with sea ice," Ainley said. "They
have an incredible ability to lay on layers of fat when the sea ice is heavy."

For example, he said, Adelies can hold their breath for six minutes at a time
and Emperors can go without a breath for 20 minutes at a time, allowing both
species to forage for food underneath the ice.

They eat fish, squid and tiny creatures called krill.

Adelie penguins have moved around depending on the temperature at least since
the so-called Little Ice Age that occurred around the year 1200, Ainley said.

"As the Earth cooled slightly, Adelie colonies began to appear further north
during the Little Ice Age," he said. "But since then, Adelies have been
retreating, and in the past 30 years this process has been accelerating."

When asked whether there is any doubt that this is a consequence of
human-fuelled global warming, Ainley offered a flat "No" in reply.

ROCK THIEVES

To keep track of the Adelie colonies at three sites in the vicinity of McMurdo
Station, Ainley and his team band hundreds of the new chicks and insert bar code
identifying chips under the skin near the shoulders of the adults.

"You'd never be able to collect any meaningful data without these techniques,"
he explained, noting that you might be able to weigh a certain penguin once, but
it would be virtually impossible to identify that penguin again for a repeat
weighing.

As it is, scientists have constructed a weigh bridge that acts as a scale when
penguins waddle across it.

Because nothing grows on the sea ice where Adelies live, there are no twigs or
branches to build nests, so these penguins collect rocks and fashion a nest-like
pile of them to brood over their eggs -- usually two eggs at a time.

Even rocks are in short supply, so some Adelies have a habit of swiping rocks
from other penguins' nests, Ainley said.

"Some birds are pretty industrious," he said. "Others have a strategy of
stealing."


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